Inductor

ABSTRACT

An inductor includes a coil having a plurality of coil patterns and external electrodes connected thereto. An innermost coil pattern and an outermost coil pattern in the coil grow using first and second insulating wall as growth guides and the inductor has a structure in which there is no deviation in thickness and shape between the coil patterns.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application claims benefit of priority to Korean Patent ApplicationNo. 10-2017-0094148 filed on Jul. 25, 2017 in the Korean IntellectualProperty Office, the disclosure of which is incorporated herein byreference in its entirety.

TECHNICAL FIELD

The present disclosure relates to an inductor, and more particularly, toa thin film type power inductor.

BACKGROUND

In accordance with the development of information technology (IT),apparatuses have been rapidly miniaturized and thinned. Therefore,market demand for small, thin devices has increased.

Korean Patent Laid-Open Publication No. 10-1999-0066108 provides a powerinductor including a substrate having a via hole and coils disposed onopposite surfaces of the substrate and electrically connected to eachother through the via hole of the substrate in accordance with atechnical trend to make an effort to provide an inductor including coilshaving uniform and high aspect ratios. However, there is still alimitation informing coils having uniform high aspect ratios due tolimitations in a manufacturing process.

SUMMARY

An aspect of the present disclosure may provide an inductor includingcoil patterns having a high aspect ratio while improving direct currentresistance (Rdc) distribution by decreasing a difference in thicknessbetween a plurality of coil patterns in a coil.

According to an aspect of the present disclosure, an inductor mayinclude: a body; and first and second external electrodes disposed on anexternal surface of the body. The body may include a support member; acoil supported by the support member; first and second insulating walls;and an insulating film simultaneously enclosing the coil and the firstand second insulating walls. Each of the first and second insulatingwalls may be formed of a single integrated insulating wall without aninternal boundary surface.

BRIEF DESCRIPTION OF DRAWINGS

The above and other aspects, features, and advantages of the presentdisclosure will be more clearly understood from the following detaileddescription taken in conjunction with the accompanying drawings, inwhich:

FIG. 1 is a schematic perspective view illustrating an inductoraccording to an exemplary embodiment in the present disclosure; and

FIG. 2 is a schematic cross-sectional view taken along line I-I′ of FIG.1.

DETAILED DESCRIPTION

Hereinafter, exemplary embodiments of the present disclosure will now bedescribed in detail with reference to the accompanying drawings.

Hereinafter, an inductor according to an exemplary embodiment in thepresent disclosure will be described. However, the present disclosure isnot necessarily limited thereto.

Inductor

FIG. 1 is a schematic perspective view illustrating an inductoraccording to an exemplary embodiment in the present disclosure, and FIG.2 is a cross-sectional view taken along line I-I′ of FIG. 1.

Referring to FIGS. 1 and 2, an inductor 100 according to the exemplaryembodiment may include a body 1 configuring an entire exterior of theinductor and first and second external electrodes 21 and 22 disposed onan external surface of the body 1.

The body 1 may have upper and lower surfaces opposing each other in athickness (T) direction, first and second end surfaces opposing eachother in a length (L) direction, and first and second side surfacesopposing each other in a width (W) direction, and be substantiallyhexahedron. However, an external shape of the body is not limited.

The body 1 may contain a magnetic material. For example, the body 1 maybe formed by filling a ferrite material or a metal based soft magneticmaterial. An example of the ferrite may include ferrite known in the artsuch as Mn—Zn based ferrite, Ni—Zn based ferrite, Ni—Zn—Cu basedferrite, Mn—Mg based ferrite, Ba based ferrite, Li based ferrite, or thelike. The metal based soft magnetic material may be an alloy containingat least one selected from the group consisting of Fe, Si, Cr, Al, andNi. For example, the metal based soft magnetic material may containFe—Si—B—Cr based amorphous metal particles, but is not limited thereto.The metal based soft magnetic material may have a particle diameter of0.1 μm or more to 20 μm or less and be contained in a form in which themetal based soft magnetic material is dispersed in a polymer such as anepoxy resin, polyimide, or the like.

A support member 11 may be disposed in the body 1 and serve to suitablysupport a coil while allowing the coil to be easily formed. As thesupport member, a support member having insulating properties and a thinfilm shape may be suitably used. For example, a general copper cladlaminate (CCL) substrate, or the like, may be used. Specifically, thesupport member 11 may have a thickness sufficient to support the coil.For example, preferably, the support member 11 may have a thickness ofabout 60 μm or so. Further, a through hole H may be included in acentral portion of the support member 11, and since a magnetic materialis filled in the through hole H, a magnetic flux of the coil may beimproved.

Next, a coil 12 including a plurality of coil patterns 121, 122 a, 122b, and 123 on an upper surface of the support member, supported by thesupport member, and first and second insulating walls 131 and 132adjacent to an outermost coil pattern 123 and an innermost coil pattern121 among the coil patterns will be described. The coil 12 may includean upper coil disposed on the upper surface of the support member 11 anda lower coil disposed on a lower surface of the support member 11, andthe upper and lower coils may be electrically connected to each otherthrough a via V in the support member. However, for convenience ofexplanation, the coil 12 will be described based on the upper coil. Ofcourse, a description of the coil to be provided below may be applied tothe lower coil as it is.

Preferably, the coil 12 may have an overall spiral shape and have, onaverage, an aspect ratio of 1.0 or more. An aspect ratio is define to bea ratio of a thickness (or a height) to a width. The coil 12 may includethe plurality of coil patterns. Among them, each of the innermost coilpattern 121 most adjacent to the through hole and the outermost coilpattern 123 most adjacent to the external surface of the body may comeinto at least partial contact with the first and second insulating walls131 and 132 adjacent thereto. In detail, at least a portion of a sidesurface of the innermost coil pattern 121 may come into contact with thefirst insulating wall 131. Although a case in which the side surface ofthe innermost coil pattern 121 entirely comes into contact with thefirst insulating wall 131 is illustrated in FIG. 2, the innermost coilpattern 121 is not limited thereto. That is, only at least a portion ofthe side surface may partially come into contact with the firstinsulating wall 131. Particularly, when a width of a lower portion ofthe innermost coil pattern is wider than that of an upper portionthereof, the upper portion of the innermost coil pattern may come intocontact with the first insulating wall, but the lower portion thereofmay be spaced apart from the first insulating wall by a predeterminedinterval. Similarly, at least a portion of a side surface of theoutermost coil pattern 123 may come into contact with the secondinsulating wall 132. Although a case in which the side surface of theoutermost coil pattern 123 entirely comes into contact with the secondinsulating wall 132 is illustrated in FIG. 2, the outermost coil pattern123 is not limited thereto. That is, only at least a portion of the sidesurface of the outermost coil pattern 123 may partially come intocontact with the second insulating wall 132. Particularly, when a widthof a lower portion of the outermost coil pattern is wider than that ofan upper portion thereof, the upper portion of the outermost coilpattern may come into contact with the second insulating wall, but thelower portion thereof may be spaced apart from the second insulatingwall by a predetermined interval.

Thicknesses t1 of the first and second insulating walls 131 and 132 maybe approximately 200 μm or more, but are not limited thereto and may besuitably selected by those skilled in the art. Since the first andsecond insulating walls are formed of single integrated insulating wallseven though the first and second insulating walls are significantlythick insulating walls (having a thickness of approximately 200 μm ormore), problems caused in a case of forming a plurality of insulatingwalls may be entirely solved. The first and second insulating walls 131and 132 may have an aspect ratio of 3.0 or more. For example, a width w1of the first and second insulating walls 131 and 132 in the widthdirection may be approximately 20 to 50 μm. In addition, preferably, thethickness of the first insulating wall may be greater than a height ofan uppermost surface of the innermost coil pattern adjacent thereto, andthe thickness of the second insulating wall may be equal to or greaterthan a height of an uppermost surface of the outermost coil patternadjacent thereto. The reason is that this case is advantageous forallowing the coil pattern to stably grow using the first and secondinsulating walls as guides and allowing a structure of the coil patternto uniformly grow. The first and second insulating walls 131 and 132 maynot contain concave and convex portions in a growth direction of thecoil pattern.

Meanwhile, each of the coil patterns 121, 122 a, 122 b, and 123 mayinclude a seed layer 12 s coming in contact with the support member 11and a plurality of plating layers 12 p 1, 12 p 2, . . . formed on theseed layer 12 s. Boundaries between the seed layer and each of theplating layers in the plurality of plating layers may be confirmed by amicroscope such as a scanning electron microscope (SEM), or the like. Amethod of manufacturing the seed layer 12 s is not limited and anelectroless plating method, a sputtering method, a chemical etchingmethod, or the like, may be suitably selected by those skilled in theart in consideration of process conditions, product specifications, andthe like. Preferably, a width of the seed layer 12 s in the widthdirection (a maximum width of the seed layer 12 s in a case in which awidth of the seed layer 12 s is changed in the thickness direction) maybe equal to or smaller than a maximum width of the plurality of platinglayers disposed thereon. However, since the first and second insulatingwalls 131 and 132 are disposed at the outside the coil (the inside ofthe innermost coil pattern and the outside of the outermost coilpattern), in a case of performing anisotropic plating on the seed layer,a flow rate (Cu²⁺) supplied to each of the seed layers are equal,thereby preventing an over-plating layer from being formed as a platinglayer of a specific coil pattern. Therefore, a difference between thewidth of the seed layer and the maximum width of the plating layer onthe seed layer is not large.

Further, the plurality of plating layers 12 p 1, 12 p 2, . . . may beformed by a suitable combination of anisotropic plating and isotropicplating. FIG. 2 illustrates a case in which a first plating layer 12 p 1is formed on the seed layer 12 s by performing the isotropic plating andthen second and third plating layers 12 p 2 and 12 p 3 are formed bycontinuously performing the anisotropic plating two times.

Referring to FIG. 2, alignments between the first plating layers, thesecond plating layers, and the third plating layers may substantiallycoincide with each other. Here, the alignments substantially coincidewith each other may mean that virtual lines along the thicknessdirection connecting the centers of lower portions of respective platinglayers to the centers of upper portions of the respective plating layerssubstantially coincide with each other. The reason is that the first andsecond insulating layers have an aspect ratio of 3.0 or more and aheight of about 200 μm or more, and each of the first and secondinsulating walls is formed of a single integrated insulating wallwithout an internal boundary surface. At least one internal boundarysurface is present in the first and second insulating walls, which meansthat a plurality of processes are required to form the first and secondinsulating walls. To this end, there is a need to control alignmentsbetween respective plating layers again. Therefore, it may besignificantly difficult to control alignments between two or moreplating layers among the first to third plating layers. Since in theinductor according to the present disclosure, the insulating wall isformed of the single insulating wall, at the time of forming therespective plating layers, a process of forming an insulating wall isnot included. Therefore, there is no difficulty in controllingalignments between the respective plating layers. Further, there is nopossibility that abnormalities will occur in shapes of the first andsecond insulating walls, and since the first and second insulating wallsremain in a chip of a final inductor as they are, an unpeeling defectoccurring at the time of removing the insulating wall in the vicinity ofa lead portion of the coil adjacent to the second insulating wall may beprevented in advance.

In addition, referring to FIG. 2, widths of the first plating layer, thesecond plating layer, and the third plating layer in the width directionmay be substantially equal to each other, which means that over-platingis not formed in a specific coil pattern. Generally, an anisotropicplating method is a method adopted at the time of forming a seed patternand then implementing the rest thickness of the coil in order toimplement a required aspect ratio. In this case, uniformity ofthicknesses and shapes of coil patterns tends to be frequentlydeteriorated, thereby having a negative influence on Rdc distribution.Further, when a shape of the coil pattern is grown abnormally, the coilpattern may be bent, and thus, as a spaced distance between the coilpatterns is gradually decreased, a risk that a short circuit will occurmay be increased. As a result, in a case of restricting growth of thecoil pattern in order to prevent the short circuit, it may be impossibleto obtain a coil having a high aspect ratio. However, since the firstand second insulating walls of the inductor according to the exemplaryembodiment in the present disclosure have smooth side surfaces and areformed of single integrated insulating walls and thus widths of theupper and lower portions thereof are substantially equal to each other,even in a case of alternately performing the isotropic plating and/oranisotropic plating several times, the flow rate supplied to the seedlayer may be uniformly controlled, such that width and thicknessdistribution caused by plating growth may be significantly controlled.As a result, the widths of the first plating layer (isotropic plating),the second plating layer (anisotropic plating), and the third platinglayer (anisotropic plating) may be substantially equal to each other.

Next, an insulating film 14 filling spaces between the plurality of coilpatterns and covering upper surfaces of the plurality of coil patternswill be described. Since the insulating film 14 encloses upper surfacesand side surfaces of the first and second insulating walls 131 and 132,the inductor may have a double insulating structure. Insulation betweenthe coil patterns and between the coil pattern and the magnetic materialmay be more clearly secured through the double insulating structure asdescribed above. The first and second insulating walls 131 and 132 maycontain a permanent type photosensitive insulating material, forexample, a photosensitive material containing a bisphenol based epoxyresin as a main ingredient. Here, the bisphenol based epoxy resin maybe, for example, a bisphenol A novolac epoxy resin, a bisphenol Adiglycidyl ether bisphenol A polymer resin, or the like, but is notlimited thereto. Any material may be used as long as it is a generalpermanent type resist material.

Meanwhile, the insulating film may be implemented by a method known inthe art. For example, the insulating film may be formed by a spraymethod or a chemical vapor deposition method. Preferably, the insulatingfilm may have a structure corresponding to shapes of the upper convexsurfaces of the coil pattern disposed below the insulating film. In thiscase, a thickness of the insulating film may be significantly decreased,such that an unnecessary space required to form the insulating film maybe significantly decreased, and a space filled with the magneticmaterial may be sufficiently secured. A material of the insulating filmis not particularly limited and may be suitably selected depending on aused method and use conditions. For example, the insulating film maycontain a perylene resin.

The insulating film 14 may serve to fill the spaces between theplurality of coil patterns to prevent a short circuit between the coilpatterns. Since uniformity of the shapes and widths of the upper andlower portions of each of the coil patterns is substantially maintained,there is no risk of a defect that the insulating film will not be formedup to the lower portions of the coil pattern. The insulating film 14,the, the first and second insulating walls 131 and 132, and the magneticmaterial forming the body 1 may made of different materials.

Referring back to FIG. 1, the first and second external electrodes 21and 22 disposed on the external surface of the body 1 and connected tothe coil may have an alphabet C shape, but are not limited thereto. Ifnecessary, the shapes of the first and second external electrodes 21 and22 may be suitably by those skilled in the art. Since the first andsecond external electrodes 21 and 22 are electrically connected to thecoil, the first and second external electrodes 21 and 22 need to beformed of a material having excellent electrical conductivity. The firstand second external electrodes may also contain a conductive resin, andmay also include pre-plating layers in order to increase a contact areawith the coil to decrease Rdc.

With the inductor described above, the aspect ratio of the coil may besignificantly increased, and uniformity of the widths andcross-sectional shapes of the coil pattern, and the like, may beimproved. As a result, Rdc distribution may be improved, a high aspectratio and insulation reliability may be simultaneously secured, and anunnecessary process such as a process of removing the insulating wall,or the like, may be omitted, such that economical efficiency in theprocess may be secured.

As set forth above, according to exemplary embodiments in the presentdisclosure, the inductor including the coil having a higher aspect ratioto decrease Rdc while improving thickness distribution of the coilpatterns to improve Rdc distribution may be provided.

While exemplary embodiments have been shown and described above, it willbe apparent to those skilled in the art that modifications andvariations could be made without departing from the scope of the presentinvention as defined by the appended claims.

What is claimed is:
 1. An inductor comprising: a body including: asupport member including a through hole, a coil including a plurality ofcoil patterns disposed on the support member and connected to each otherto have an overall spiral shape, each of the plurality of coil patternsincluding a first plating layer and a second plating layer stacked onthe first plating layer, a first insulating wall being at least partialcontact with an innermost coil pattern among the plurality of coilpatterns, a second insulating wall being at least partial contact withan outermost coil pattern among the plurality of coil patterns, and aninsulating film filling spaces between the plurality of coil patternsand covering upper surfaces of the first and second insulating walls;and first and second external electrodes disposed on an external surfaceof the body and connected to the coil, wherein each of the first andsecond insulating walls is a single insulating layer, the firstinsulating wall includes a distal portion spaced apart from the supportmember and from the first and second plating layers of the innermostcoil pattern, and the second insulating wall includes a distal portionspaced apart from the support member and from the first and secondplating layers of the outermost coil pattern.
 2. The inductor of claim1, wherein an entire side surface of the innermost coil pattern iscontact with the first insulating wall, and an entire side surface ofthe outermost coil pattern is contact with the second insulating wall.3. The inductor of claim 1, wherein the first insulating wall extends toa position equal to or higher than a position of an uppermost surface ofthe innermost coil pattern, and the second insulating wall extends to aposition equal to or higher than a position of an uppermost surface ofthe outermost coil pattern.
 4. The inductor of claim 1, wherein theinsulating film encloses all surfaces of the first and second insulatingwalls that do not contact with the innermost coil pattern or theoutermost coil pattern among surfaces of the first and second insulatingwalls.
 5. The inductor of claim 1, wherein each of the first and secondinsulating walls has an aspect ratio of 3.0 or more.
 6. The inductor ofclaim 1, wherein a virtual line connecting the center of a lower surfaceof the first plating layer to the center of an upper surface thereofcoincides with a virtual line connecting the center of a lower surfaceof the second plating layer to the center of an upper surface thereof.7. The inductor of claim 1, wherein a portion of the insulating filmdisposed on upper surfaces of the plurality of coil patterns has a shapecorresponding to the upper surfaces of the plurality of coil patterns.8. The inductor of claim 1, wherein the first and second insulatingwalls contain a permanent type epoxy-based insulating material.
 9. Theinductor of claim 1, wherein the first and second insulating walls donot contain concave and convex portions in a growth direction of thecoil pattern.
 10. The inductor of claim 1, wherein the first and secondinsulating walls and the insulating film are made of materials differentfrom each other.
 11. The inductor of claim 1, wherein each of theplurality of coil patterns has a convex upper surface.
 12. The inductorof claim 1, wherein a magnetic material is provided on the supportmember and a surface of the insulating film.
 13. The inductor of claim1, wherein the coil includes an upper coil formed on an upper surface ofthe support member and a lower coil formed on a lower surface of thesupport member, and the upper and lower coils are electrically connectedto each other through a via in the support member.
 14. The inductor ofclaim 1, wherein each of the plurality of coil patterns is composed of aseed layer and a plurality of plating layers formed on the seed layer.15. The inductor of claim 14, wherein the seed layer is disposed on anupper surface of the support member, and except for a surface of theseed layer being in contact with the support member, the other surfacesof the seed layer are enclosed by the plurality of plating layers. 16.The inductor of claim 14, wherein among the plurality of plating layers,a plating layer disposed directly on the seed layer is an isotropicplating layer, and the other plating layers are anisotropic platinglayers.
 17. The inductor of claim 14, wherein a thickness of the firstinsulating wall is greater than a sum of thicknesses of the seed layerand the first and second plating layers of the innermost coil pattern,and a thickness of the second insulating wall is greater than a sum ofthicknesses of the seed layer and the first and second plating layers ofthe outermost coil pattern.
 18. An inductor comprising: a bodyincluding: a support member including a through hole, a coil including aplurality of coil patterns disposed on the support member and connectedto each other to have an overall spiral shape, each of the plurality ofcoil patterns including a first plating layer and a second plating layerstacked on the first plating layer, a first insulating wall being atleast partial contact with an innermost coil pattern among the pluralityof coil patterns, a second insulating wall being at least partialcontact with an outermost coil pattern among the plurality of coilpatterns, and an insulating film filling spaces between the plurality ofcoil patterns and covering upper surfaces of the first and secondinsulating walls; and first and second external electrodes disposed onan external surface of the body and connected to the coil, wherein thefirst insulating wall linearly extends from the support member, and iscontact with the first and second plating layers of the innermost coilpattern, and the second insulating wall linearly extends from thesupport member, and is contact with the first and second plating layersof the outermost coil pattern.
 19. The inductor of claim 18, whereineach of the first and second insulating wall is a single insulatinglayer.
 20. The inductor of claim 18, wherein the first and secondinsulating walls and the insulating film are made of materials differentfrom each other.